A. When two actions by the same subject occur simultaneously it is usually possible to express one of them by a present participle. The participle can be before or after the finite verb.

e.g. He rode away. He whistled as he went. = He rode away whistling.

B. When one action is immediately followed by another by the same subject the first action can often be expressed by a present participle. The participle must be put first.

e.g. He opened the drawer and took out a revolver.= Opening the drawer and took out a revolver.

It would seem more logical here to use the perfect participle and say Having opened, but this is not necessary except when the use of the present participle might lead to ambiguity¡£

C. When the second action forms part of the first, or are a result of it, we can express the second action by a present participle. e.g. She went out, slamming the door.